Chronic obstructive pulmonary disease (COPD) is known to include emphysema predominant COPD and airway disease predominant COPD. In the case of emphysema predominant COPD, lung tissue is broken down by toxic substances for example, and the resultant reduction in alveoli leads to reduction in the force of supporting bronchi, which makes it difficult to expand the bronchi. In the case of airway disease predominant COPD, some of the bronchi are narrowed by factors other than emphysema, which results in airflow obstruction.
In the case of emphysema predominant COPD, an emphysematous lesion is extracted as a low attenuation area (LAA) with high-resolution (HR) computed tomography (CT). A ratio of the low attenuation area to an entire lung determines advance degree and severity of the emphysema.
On the contrary, since airway disease predominant COPD involves thickened airway walls and narrowed lumens, axial images are used for diagnosis, so that states of airways are visually observed by an operator.
In this connection, for example, a medical image processing apparatus is being examined which is configured to generate a curved multi-planar reconstruction image including images of many abnormal spots.
It is also being examined to visually observe a large number of cross sections of a bronchus and to numerically calculate and display a cross-sectional area for the purpose of bronchial analysis.
However, in the case of, for example, calculating cross sections of a bronchial outer wall and a bronchial inner wall and calculating area ratios therebetween to perform diagnostic reading of the cross sections with axial images, the area ratios are presented only in the form of numerical values. Accordingly, when one area ratio is displayed on a certain image, it is impossible to identify which location the displayed area ratio relates to in the entire image. Moreover, when diagnostic reading is performed with axial images, bronchi are displayed as tubular structures equivalent to blood vessels, which makes it difficult to instantaneously discriminate a bronchus that is a target of diagnostic reading.